A coupling (20) capable of connecting together two piping sections (30, 30) having the same outer diameter, two piping sections (40, 40) having the same inner diameter, or two piping sections (30, 40) having different diameters. The coupling (20) can have a unitary tubular structure and it can be made of the same material and in the same manner as conventional PVC piping. Installation of the coupling (20) during construction of a passageway can be accomplished in same manner as is conventionally accomplished with three distinct types of coupling.